The present invention relates to a container for supplying under pressure a plurality of fluids of different colors to a color changer for spray painting equipment.
Airbrushes are commonly used by commercial artists and photographers to apply color and shading to drawings, prints and photographs, to accentuate highlights and to supply backgrounds to films, as well as by hobbyists for painting models and projects. An airbrush is usually shaped like a pencil, and as is well known utilizes air to atomize a fluid in a controlled pattern for deposit on an article.
In use of a typical airbrush, a bottle containing fluid of a color to be applied is connected to the airbrush. The bottle has an outlet hole in its cap through which fluid is aspirated into a fluid inlet to the gun and a vent hole through which air is drawn as the bottle empties so that a vacuum does not occur in the bottle and defeat further aspiration of fluid. Compressed air coupled to the airbrush passes through a small orifice adjacent the fluid inlet to the airbrush and draws the fluid out of the bottle due to the low pressure region developed across the bottle outlet as a result of venturi effect. The flow of air then atomizes the fluid into droplets and applies it onto the surface being colored.
Prior airbrush and bottle assemblies have numerous drawbacks. For each different color or blend of colors a different bottle has to be attached to the airbrush, and in the case of a blend of colors different fluids must first be mixed together. The technique is time consuming and tedious, and interrupts the flow of working with the airbrush. In addition, between color changes, a bottle of solvent has to be connected with the airbrush for flushing purposes. Moreover, the outlet holes from the bottles have a tendency to become plugged when relatively viscous fluids are used, as well as the vent holes due to the fluid being moved across the vents from the motion of the bottle during airbrushing.
To overcome the aforementioned disadvantages of airbrush and bottle assemblies, a color changer which selectively supplies different colors of fluid or a solvent to an airbrush may be used. In use of a color changer, bottles containing the fluids to be sprayed, such as bottles of ink of different colors, connect through associated fluid supply lines with inlets to the color changer, so that one or more of the fluids may be selected for supply to the airbrush. Inasmuch as it has heretofore been necessary to rely upon venturi effect to aspirate fluids into the airbrush for being atomized into a spray, so that the venturi effect will be sufficient to draw fluids into the airbrush the supply bottles of fluid must be maintained at about the working level of the airbrush. The net result is that the vertical working range of the airbrush is drastically limited, since if it is elevated sufficiently above the supply bottles, the vacuum generated by venturi effect will not be strong enough to overcome gravity and draw the fluids into the airbrush, and spraying will cease.
The arrangement also results in unacceptable variations in the flow rate of fluids to the airbrush. As the airbrush is lowered from its maximum operational height, at which point a minimal flow rate of fluids is available, the flow rate increases because of the decreasing gravitational effect which must be overcome, and continues to increase as the airbrush is lowered to and below the level of the bottles, at which point the fluids are brought to an increasingly positive pressure by gravity. In consequence, the rate at which fluids are sprayed is extremely difficult if not impossible to control, and for satisfactory results all airbrushing must be performed at a substantially constant vertical level.